The fail-safe function is a widely adopted function in the vehicle sector that may, for example, be used for detecting and warning of anomalous behavior of a function of a vehicle. This warning is to prevent, in the presence of a failure, situations that are dangerous for the occupants of a vehicle from arising. In various possible implementations, a device capable of providing such a function, in the case where it detects a fault, can enter a fail-safe mode in which, for example, an external safety logic and/or an additional microcontroller assume/assumes control of the safety circuits for ensuring that the system enters/evolves in a safe state, that is not dangerous for the occupants.
The specific characteristics of safety involved may depend upon the application. For instance, in the case of applications to the door zone, the motorized window function may be considered important for safety in so far as, for example, an erroneous or undesired operation may prove quite harmful for the occupants.
Various implementations may envision a fail-safe logic comprising a power-management device and various external components. To provide a fail-safe function (e.g. to keep a window-regulator deactivated), one or more implementations may require external components, which are to be activated only if a failure in the power-management function is detected. In the presence of lack of operation, for example, of the logic contained in the device for operating the window-regulator (generically referred to as “door zone”), with such implementations, there may not be entry into action of the fail-safe circuit.
There may arise situations in which the fail-safe function is activated only in the presence of detectable failures within the power-management function such as, for example: a failure of the so-called watchdog function (Watchdog Failure); a failure of the power supply (V1 under-voltage); and triggering of a thermal-safety function (for example, second thermal shutdown level—TSD2). It will likewise be noted that there cannot be an activation of the fail-safe function in the presence of a failure in the door actuation device, for example, owing to malfunctioning of the logic circuitry or to triggering of a thermal safety device. Various implementations may be based upon using two distinct chips, but it may instead be desirable to have available single chip solutions.